Population-based epidemiologic studies of communities in the United States have revealed a consistent association between ambient particulate air pollution and increases in morbidity and mortality. The observed increases result from both respiratory and cardiovascular diseases for subjects over age 65. These ambient exposures are to levels of particulates many times lower than occupational exposures faced by workers in a variety of industries, including manufacturing, construction, transportation and electric-power generation. The objective of this proposal is to investigate the role of occupational exposure to particulates in the development of respiratory and cardiac responses in boilermakers with and without chronic bronchitis. We will employ a detailed continuous-exposure assessment to PM2.5 with repeated measures of biologic and physiologic markers of response. Specific hypotheses to be tested will include: (1) occupational exposure to fuel-oil ash particulates and associated metals induce airway inflammation as reflected in decreases in peak flow (PEFR) and FEV1; (2) particulate exposure and associated metals will result in acute changes in cardiovascular function, as reflected in changes in heart rate, heart-rate variability and blood pressure; (3) particulate metal exposure will result in increased serum fibrinogen levels, a known risk factor for cardiovascular disease; and (4) chronic bronchitis predisposes exposed workers to changes in cardiac function. The experimental approach will be an epidemiologic study employing a prospective, repeated measures design assessing several biologic parameters in relation to exposure. The expected results will clarify the relationship between exposure to oil-combustion ash metals and human cardiopulmonary responses in both normal and chronic bronchitic populations. Clarification of such exposure-response relationships will have important implications for preventive efforts aimed at reducing morbidity and mortality form exposure to respirable particulates and their associated metals.